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• Succinct introduction to C++/CLI for C#/Haskell/F#/JS/C++/... programmer

  - by Henrik

  Hello everybody, I'm trying to write integrations with the operating system and with things like active directory and Ocropus. I know a bunch of programming languages, including those listed in the title. I'm trying to learn exactly how C++/CLI works, but can't find succinct, exact and accurate descriptions online from the searching that I have done. So I ask here. Could you tell me the pitfalls and features of C++/CLI? Assume I know all of C# and start from there. I'm not an expert in C++, so some of my questions' answers might be "just like C++", but could say that I am at C#. I would like to know things like: Converting C++ pointers to CLI pointers, Any differences in passing by value/doubly indirect pointers/CLI pointers from C#/C++ and what is 'recommended'. How do gcnew, __gc, __nogc work with Polymorphism Structs Inner classes Interfaces The "fixed" keyword; does that exist? Compiling DLLs loaded into the kernel with C++/CLI possible? Loaded as device drivers? Invoked by the kernel? What does this mean anyway (i.e. to load something into the kernel exactly; how do I know if it is?)? L"my string" versus "my string"? wchar_t? How many types of chars are there? Are we safe in treating chars as uint32s or what should one treat them as to guarantee language indifference in code? Finalizers (~ClassName() {}) are discouraged in C# because there are no garantuees they will run deterministically, but since in C++ I have to use "delete" or use copy-c'tors as to stack allocate memory, what are the recommendations between C#/C++ interactions? What are the pitfalls when using reflection in C++/CLI? How well does C++/CLI work with the IDisposable pattern and with SafeHandle, SafeHandleZeroOrMinusOneIsInvalid? I've read briefly about asynchronous exceptions when doing DMA-operations, what are these? Are there limitations you impose upon yourself when using C++ with CLI integration rather than just doing plain C++? Attributes in C++ similar to Attributes in C#? Can I use the full meta-programming patterns available in C++ through templates now and still have it compile like ordinary C++? Have you tried writing C++/CLI with boost? What are the optimal ways of interfacing the boost library with C++/CLI; can you give me an example of passing a lambda expression to an iterator/foldr function? What is the preferred way of exception handling? Can C++/CLI catch managed exceptions now? How well does dynamic IL generation work with C++/CLI? Does it run on Mono? Any other things I ought to know about?

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• Mixing application modules between Silverlight and ASP.NET

  - by jkohlhepp

  Background: I work in a suite of ASP.NET applications that have several different "modules". The applications all share a main menu, so they all link to one-another. The modules are the high-level areas of the application. So, for example, it might be Payments, Orders, Customers, Products, etc. And Payments and Orders are in one app and Products and Customers are in another. Some of these menu links are "deep links", for example it might be a link to a particular page within the Customers module, such as Create New Customer. The issue: We are about to start a project that will add several more modules to this suite, probably as a new .NET application. I'm thinking about doing these new modules in Silverlight (for various reasons that are not material to the question). If I were to do that, I need to make the menu look the same as the menu in ASP.NET, as the users still need to feel like they are inside one "application". My questions: How should I organize the Silverlight project(s) so that I can "deep link" from ASP.NET pages into particular modules in the Silverlight app? What is even the best idea for creating these different Silverlight "modules"? If I had something that would've been a page in ASP.NET (for example - Create Customer), should each one of those be a separate Silverlight app? Or should it be a separate User Control? Or something else? Should I reuse our shared ASP.NET menu, and deep link to different Silverlight "modules" even within the new application? Or should I reimplement the menu in Silverlight for navigation within the app? Are there menu controls for Silverlight that look similar to ASP.NET menus (with flyout submenus in this case)? Could I maybe even share a SiteMap XML file between them? Edit: After looking around a bit more, it seems like PRISM might be the answer for some of my issues. It would allow me to modularize the different chunks of Silverlight that I have. And it would allow me to define a "master page" in Silverlight where I could host the menu. Do I have this right?

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• PriorityQueue update problems

  - by Bharat

  After going through a bunch of questions here on SO, I still have no idea what exactly is going wrong with my code and would appreciate some help. I'm trying to implement a priority queue based on f-costs for an A* algorithm, and while the algorithm works fine for short pathfinding distances, it seems to go wrong when there's an obstacle or when the distance between start and goal points is greater than about 30 squares (although sometimes it screws up for less too). while(!m_qOpenList.isEmpty()) { m_xCurrent=m_qOpenList.poll(); m_xCurrent.setBackground(Color.red); m_qClosedList.add(m_xCurrent); if(m_xCurrent.getStatus()==2) { System.out.println("Target Reached"); solved=true; break; } iX=m_xCurrent.getXCo(); iY=m_xCurrent.getYCo(); for(i=iX-1;i<=iX+1;i++) for(j=iY-1;j<=iY+1;j++) { if(i<0||j<0||i>m_iMazeX||j>m_iMazeX||(i==iX&&j==iY) || m_xNode[i][j].getStatus()==4|| m_qClosedList.contains(m_xNode[i][j])) continue; m_xNode[i][j].score(m_xCurrent,m_xGoal); m_qOpenList.add(m_xNode[i][j]); } } It's quite rudimentary as I'm just trying to get it to work for now. m_qOpenList is the PriorityQueue. The problem is that when I debug the program, at some point (near an obstacle), a Node with a fcost of say 84 has higher priority than a node with an fcost of 70. I am not attempting to modify the values once they're on the priority queue. You'll notice that I add at the end of the while loop (I read somewhere that the priorityqueue reorders itself when stuff is added to it), and poll right after that at the beginning. Status of 2 means the Node is the goal, and a status of 4 means that it is unwalkable. public int compareTo(Node o) { if(m_iF<o.m_iF) return -1; if(m_iF>o.m_iF) return 1; return 0; } And that's the compareTo function. Can you see a problem? =(

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• How can I take the first 100 characters of html content ( without stripping the TAGS! )

  - by Atomiton

  There are lots of questions on how to strip html tags, but not many on functions/methods to close them. Here's the situation. I have a 500 character Message summary ( which includes html tags ), but I only want the first 100 characters. Problem is if I truncate the message, it could be in the middle of an html tag... which messes up stuff. Assuming the html is something like this: <div class="bd">"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. <br/> <br/>Some Dates: April 30 - May 2, 2010 <br/> <p>Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. <em>Duis aute irure dolor in reprehenderit</em> in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. <br/> </p> For more information about Lorem Ipsum doemdloe, visit: <br/> <a href="http://www.somesite.com" title="Some Conference">Some text link</a><br/> </div> How would I take the first ~100 characters or so? ( Although, ideally that would be the first approximately 100 characters of "CONTENT" ( in between the html tags ) I'm assuming the best way to do this would be a recursive algorithm that keeps track of the html tags and appends any tags that would be truncated, but that may not be the best approach. My first thoughts are using recursion to count nested tags, and when we reach 100 characters, look for the next "<" and then use recursion to write the closing html tags needed from there. The reason for doing this is to make a short summary of existing articles without requiring the user to go back and provide summaries for all the articles. I want to keep the html formatting, if possible. NOTE: Please ignore that the html isn't totally semantic. This is what I have to deal with from my WYSIWYG. EDIT: I added a potential solution ( that seems to work ) I figure others will run into this problem as well. I'm not sure it's the best... and it's probably not totally robust ( in fact, I know it isn't ), but I'd appreciate any feedback

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• Is Ogre's use of Exceptions a good way of using them?

  - by identitycrisisuk

  I've managed to get through my C++ game programming career so far virtually never touching exceptions but recently I've been working on a project with the Ogre engine and I'm trying to learn properly. I've found a lot of good questions and answers here on the general usage of C++ exceptions but I'd like to get some outside opinions from here on whether Ogre's usage is good and how best to work with them. To start with, quoting from Ogre's documentation of it's own Exception class: OGRE never uses return values to indicate errors. Instead, if an error occurs, an exception is thrown, and this is the object that encapsulates the detail of the problem. The application using OGRE should always ensure that the exceptions are caught, so all OGRE engine functions should occur within a try{} catch(Ogre::Exception& e) {} block. Really? Every single Ogre function could throw an exception and be wrapped in a try/catch block? At present this is handled in our usage of it by a try/catch in main that will show a message box with the exception description before exiting. This can be a bit awkward for debugging though as you don't get a stack trace, just the function that threw the error - more important is the function from our code that called the Ogre function. If it was an assert in Ogre code then it would go straight to the code in the debugger and I'd be able to find out what's going on much easier - I don't know if I'm missing something that would allow me to debug exceptions already? I'm starting to add a few more try/catch blocks in our code now, generally thinking about whether it matters if the Ogre function throws an exception. If it's something that will stop everything working then let the main try/catch handle it and exit the program. If it's not of great importance then catch it just after the function call and let the program continue. One recent example of this was building up a vector of the vertex/fragment program parameters for materials applied to an entity - if a material didn't have any parameters then it would throw an exception, which I caught and then ignored as it didn't need to add to my list of parameters. Does this seem like a reasonable way of dealing with things? Any specific advice for working with Ogre is much appreciated.

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• SilverLight 3 Beginner question: Scroll with mousewheel and zoom image with panning

  - by JP Hellemons

  Hello, I would like to make a small silverlight app which displays one fairly large image which can be zoomed in by scrolling the mouse and then panned with the mouse. it's similar to the function in google maps and i do not want to use deepzoom. here is what i have at the moment. please keep in mind that this is my first silverlight app: this app is just for me to see it's a good way to build in a website. so it's a demo app and therefor has bad variable names. the initial image is 1800px width. private void sc_MouseWheel(object sender, MouseWheelEventArgs e) { var st = (ScaleTransform)plaatje.RenderTransform; double zoom = e.Delta > 0 ? .1 : -.1; st.ScaleX += zoom; st.ScaleY += zoom; } this works, but could use some smoothing and it's positioned top left and not centered. the panning is like this: found it @ http://stackoverflow.com/questions/741956/wpf-pan-zoom-image and converted it to this below to work in silverlight Point start; Point origin; bool captured = false; private void plaatje_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { plaatje.CaptureMouse(); captured = true; var tt = (TranslateTransform)((TransformGroup)plaatje.RenderTransform) .Children.First(tr => tr is TranslateTransform); start = e.GetPosition(canvasje); origin = new Point(tt.X, tt.Y); } private void plaatje_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { plaatje.ReleaseMouseCapture(); captured = false; } private void plaatje_MouseMove(object sender, MouseEventArgs e) { if (!captured) return; var tt = (TranslateTransform)((TransformGroup)plaatje.RenderTransform).Children.First(tr => tr is TranslateTransform); double xVerschuiving = start.X - e.GetPosition(canvasje).X; double yVerschuiving = start.Y - e.GetPosition(canvasje).Y; tt.X = origin.X - xVerschuiving; tt.Y = origin.Y - yVerschuiving; } so the scaling isn't smooth and the panning isn't working, because when i click it, the image disappears. thanks in advanced!

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• PyQt threads and signals - how to properly retrieve values

  - by Cawas

  Using Python 2.5 and PyQt, I couldn't find any question this specific in Python, so sorry if I'm repeating the other Qt referenced questions below, but I couldn't easily understand that C code. I've got two classes, a GUI and a thread, and I'm trying to get return values from the thread. I've used the link in here as base to write my code, which is working just fine. To sum it up and illustrate the question in code here (I don't think this code will run on itself): class MainWindow (QtGui.QWidget): # this is just a reference and not really relevant to the question def __init__ (self, parent = None): QtGui.QWidget.__init__(self, parent) self.thread = Worker() # this does not begin a thread - look at "Worker.run" for mor details self.connect(self.thread, QtCore.SIGNAL('finished()'), self.unfreezeUi) self.connect(self.thread, QtCore.SIGNAL('terminated()'), self.unfreezeUi) self.connect(self.buttonDaemon, QtCore.SIGNAL('clicked()'), self.pressDaemon) # the problem begins below: I'm not using signals, or queue, or whatever, while I believe I should def pressDaemon (self): self.buttonDaemon.setEnabled(False) if self.thread.isDaemonRunning(): self.thread.setDaemonStopSignal(True) self.buttonDaemon.setText('Daemon - converts every %s sec'% args['daemonInterval']) else: self.buttonConvert.setEnabled(False) self.thread.startDaemon() self.buttonDaemon.setText('Stop Daemon') self.buttonDaemon.setEnabled(True) # this whole class is just another reference class Worker (QtCore.QThread): daemonIsRunning = False daemonStopSignal = False daemonCurrentDelay = 0 def isDaemonRunning (self): return self.daemonIsRunning def setDaemonStopSignal (self, bool): self.daemonStopSignal = bool def __init__ (self, parent = None): QtCore.QThread.__init__(self, parent) self.exiting = False self.thread_to_run = None # which def will be running def __del__ (self): self.exiting = True self.thread_to_run = None self.wait() def run (self): if self.thread_to_run != None: self.thread_to_run(mode='continue') def startDaemon (self, mode = 'run'): if mode == 'run': self.thread_to_run = self.startDaemon # I'd love to be able to just pass this as an argument on start() below return self.start() # this will begin the thread # this is where the thread actually begins self.daemonIsRunning = True self.daemonStopSignal = False sleepStep = 0.1 # don't know how to interrupt while sleeping - so the less sleepStep, the faster StopSignal will work # begins the daemon in an "infinite" loop while self.daemonStopSignal == False and not self.exiting: # here, do any kind of daemon service delay = 0 while self.daemonStopSignal == False and not self.exiting and delay < args['daemonInterval']: time.sleep(sleepStep) # delay is actually set by while, but this holds for N second delay += sleepStep # daemon stopped, reseting everything self.daemonIsRunning = False self.emit(QtCore.SIGNAL('terminated')) Tho it's quite big, I hope this is pretty clear. The main point is on def pressDaemon. Specifically all 3 self.thread calls. The last one, self.thread.startDaemon() is just fine, and exactly as the example. I doubt that represents any issue. The problem is being able to set the Daemon Stop Signal and retrieve the value if it's running. I'm not sure that it's possible to set a stop signal on QtCore.QtThread, because I've tried doing the same way and it didn't work. But I'm pretty sure it's not possible to retrieve a return result from the emit. So, there it is. I'm using direct calls to the thread class, and I'm almost positive that's not a good design and will probably fail when running under stress. I read about that queue, but I'm not sure it's the proper solution here, or if I should be using Qt at all, since this is Python. And just maybe there's nothing wrong with the way I'm doing.

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• Git for Websites / post-receive / Separation of Test and Production Sites

  - by Walt W

  Hi all, I'm using Git to manage my website's source code and deployment, and currently have the test and live sites running on the same box. Following this resource http://toroid.org/ams/git-website-howto originally, I came up with the following post-receive hook script to differentiate between pushes to my live site and pushes to my test site: while read ref do #echo "Ref updated:" #echo $ref -- would print something like example at top of file result=`echo $ref | gawk -F' ' '{ print $3 }'` if [ $result != "" ]; then echo "Branch found: " echo $result case $result in refs/heads/master ) git --work-tree=c:/temp/BLAH checkout -f master echo "Updated master" ;; refs/heads/testbranch ) git --work-tree=c:/temp/BLAH2 checkout -f testbranch echo "Updated testbranch" ;; * ) echo "No update known for $result" ;; esac fi done echo "Post-receive updates complete" However, I have doubts that this is actually safe :) I'm by no means a Git expert, but I am guessing that Git probably keeps track of the current checked-out branch head, and this approach probably has the potential to confuse it to no end. So a few questions: IS this safe? Would a better approach be to have my base repository be the test site repository (with corresponding working directory), and then have that repository push changes to a new live site repository, which has a corresponding working directory to the live site base? This would also allow me to move the production to a different server and keep the deployment chain intact. Is there something I'm missing? Is there a different, clean way to differentiate between test and production deployments when using Git for managing websites? As an additional note in light of Vi's answer, is there a good way to do this that would handle deletions without mucking with the file system much? Thank you, -Walt PS - The script I came up with for the multiple repos (and am using unless I hear better) is as follows: sitename=`basename \`pwd\`` while read ref do #echo "Ref updated:" #echo $ref -- would print something like example at top of file result=`echo $ref | gawk -F' ' '{ print $3 }'` if [ $result != "" ]; then echo "Branch found: " echo $result case $result in refs/heads/master ) git checkout -q -f master if [ $? -eq 0 ]; then echo "Test Site checked out properly" else echo "Failed to checkout test site!" fi ;; refs/heads/live-site ) git push -q ../Live/$sitename live-site:master if [ $? -eq 0 ]; then echo "Live Site received updates properly" else echo "Failed to push updates to Live Site" fi ;; * ) echo "No update known for $result" ;; esac fi done echo "Post-receive updates complete" And then the repo in ../Live/$sitename (these are "bare" repos with working trees added after init) has the basic post-receive: git checkout -f if [ $? -eq 0 ]; then echo "Live site `basename \`pwd\`` checked out successfully" else echo "Live site failed to checkout" fi

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• DoubleAnimation in ScaleTransform

  - by Adam S

  I'm trying, as an exhibition, to use a DoubleAnimation on the ScaleX and ScaleY properties of a ScaleTransform. I have a rectangle (144x144) which I want to make rectangular over five seconds. My XAML: <Window x:Class="ScaleTransformTest.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300" Loaded="Window_Loaded"> <Grid> <Rectangle Name="rect1" Width="144" Height="144" Fill="Aqua"> <Rectangle.RenderTransform> <ScaleTransform ScaleX="1" ScaleY="1" /> </Rectangle.RenderTransform> </Rectangle> </Grid> </Window> My C#: private void Window_Loaded(object sender, RoutedEventArgs e) { ScaleTransform scaly = new ScaleTransform(1, 1); rect1.RenderTransform = scaly; Duration mytime = new Duration(TimeSpan.FromSeconds(5)); Storyboard sb = new Storyboard(); DoubleAnimation danim1 = new DoubleAnimation(1, 1.5, mytime); DoubleAnimation danim2 = new DoubleAnimation(1, 0.5, mytime); sb.Children.Add(danim1); sb.Children.Add(danim2); Storyboard.SetTarget(danim1, scaly); Storyboard.SetTargetProperty(danim1, new PropertyPath(ScaleTransform.ScaleXProperty)); Storyboard.SetTarget(danim2, scaly); Storyboard.SetTargetProperty(danim2, new PropertyPath(ScaleTransform.ScaleYProperty)); sb.Begin(); } Unfortunately, when I run this program, it does nothing. The rectangle stays at 144x144. If I do away with the animation, and just ScaleTransform scaly = new ScaleTransform(1.5, 0.5); rect1.RenderTransform = scaly; it will elongate it instantly, no problem. There is a problem elsewhere. Any suggestions? I have read the discussion at http://www.eggheadcafe.com/software/aspnet/29220878/how-to-animate-tofrom-an.aspx in which someone seems to have gotten a pure-XAML version working, but the code is not shown there. EDIT: At http://stackoverflow.com/questions/2131797/applying-animated-scaletransform-in-code-problem it seems someone had a very similar problem, I am fine with using his method that worked, but what the heck is that string thePath = "(0).(1)[0].(2)"; all about? What are those numbers representing?

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• WPF - How do I get an object that is bound to a ListBoxItem back

  - by JonBlumfeld

  Hi there here is what I would like to do. I get a List of objects from a database and bind this list to a ListBox Control. The ListBoxItems consist of a textbox and a button. Here is what I came up with. Up to this point it works as intended. The object has a number of Properties like ID, Name. If I click on the button in the ListBoxItem the Item should be erased from the ListBox and also from the database... <ListBox x:Name="taglistBox"> <ListBox.ItemContainerStyle> <Style TargetType="{x:Type ListBoxItem}"> <Setter Property="HorizontalAlignment" Value="Stretch"/> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBoxItem"> <ContentPresenter HorizontalAlignment="Stretch"/> </ControlTemplate> </Setter.Value> </Setter> <Setter Property="Tag" Value="{Binding TagSelf}"></Setter> </Style> </ListBox.ItemContainerStyle> <ListBox.ItemTemplate> <DataTemplate> <Grid HorizontalAlignment="Stretch"> <Grid.ColumnDefinitions> <ColumnDefinition Width="Auto"/> <ColumnDefinition/> </Grid.ColumnDefinitions> <Button Grid.Column="0" Name="btTag" VerticalAlignment="Center" Click="btTag_Click" HorizontalAlignment="Left"> <Image Width="16" Height="16" Source="/WpfApplication1;component/Resources/104.png"/> </Button> <TextBlock Name="tbtagBoxTagItem" Margin="5" Grid.Column="1" Text="{Binding Name}" VerticalAlignment="Center" /> </Grid> </DataTemplate> </ListBox.ItemTemplate> </ListBox> The Textblock.Text is bound to object.Name and the ListBoxItem.Tag to object.TagSelf (which is just a copy of the object itself). Now my questions If I click the button in the listboxItem how do I get the listboxitem and the object bound to it back. In order to delete the object from the database I have to retrieve it somehow. I tried something like ListBoxItem lbi1 = (ListBoxItem)(taglistBox.ItemContainerGenerator.ContainerFromItem(taglistBox.Items.CurrentItem)); ObjectInQuestion t = (ObjectInQuestion) lbi1.Tag; Is there a way to automatically update the contents of the ListBox if the Itemssource changes? Right now I'm achieving that by taglistBox.ItemsSource = null; taglistBox.ItemsSource = ObjectInQuestion; I'd appreciate any help you can give :D Thanks in advance

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• Easiest Way To Get Started In Dot Net

  - by Avery Payne

  Ok, so the initial search in StackOverflow shows nothing related for this question. So here it goes: Let's pretend for a moment that you're just getting started in a career in computer programming. Let's say that, for whatever reason, you decide to use the .Net framework as a basis for your programming. Let's also say that you've been exposed to some programming background, but not one in .Net, so it seems foreign to you at first. And lastly, you don't have the benefit of 25 years of exposure to the Win32 API, which explains why it seems so foreign to you when you start looking at it. So the questions are: What is a comprehensive overview of what .Net is? It appears to be a combination of a runtime environment, a set of languages, a common set of libraries, and perhaps a few other things...so it's about as clear as mud. Specifically, what are the key components to .Net? What is the easiest way to understand .Net programming with regard to available APIs? Which language would best suit beginning programming out of the "stock" languages that Microsoft has to offer? (C++, C#, VB, etc.) What are some differences between .Net programming and programming in a procedural language (aka Pascal, Modula, etc.) What are some differences between .Net programming and programming in a "traditional" object-oriented language? (aka Smalltalk, Java, Python, Ruby, etc.) As I currently understand it, the CLR provides a foundation for all of the other languages to run on. What are some of the inherent limitations of the CLR? Given the enormous amount of API to cover, would it even be worth learning a .Net language (using the Microsoft APIs) given that you would not have prior exposure to Win32 programming? Let's say you write a for-profit program with .Net. Can you resell the program without running afoul of licensing issues? Let's say you write a gratis (free) program with .Net. Can you offer the program to the public under a "free" license (GPL, BSD, Artistic, etc.) without running afoul of licensing issues? Thank you in advance for your patience.

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• python Socket.IO client for sending broadcast messages to TornadIO2 server

  - by Alp

  I am building a realtime web application. I want to be able to send broadcast messages from the server-side implementation of my python application. Here is the setup: socketio.js on the client-side TornadIO2 server as Socket.IO server python on the server-side (Django framework) I can succesfully send socket.io messages from the client to the server. The server handles these and can send a response. In the following i will describe how i did that. Current Setup and Code First, we need to define a Connection which handles socket.io events: class BaseConnection(tornadio2.SocketConnection): def on_message(self, message): pass # will be run if client uses socket.emit('connect', username) @event def connect(self, username): # send answer to client which will be handled by socket.on('log', function) self.emit('log', 'hello ' + username) Starting the server is done by a Django management custom method: class Command(BaseCommand): args = '' help = 'Starts the TornadIO2 server for handling socket.io connections' def handle(self, *args, **kwargs): autoreload.main(self.run, args, kwargs) def run(self, *args, **kwargs): port = settings.SOCKETIO_PORT router = tornadio2.TornadioRouter(BaseConnection) application = tornado.web.Application( router.urls, socket_io_port = port ) print 'Starting socket.io server on port %s' % port server = SocketServer(application) Very well, the server runs now. Let's add the client code: <script type="text/javascript"> var sio = io.connect('localhost:9000'); sio.on('connect', function(data) { console.log('connected'); sio.emit('connect', '{{ user.username }}'); }); sio.on('log', function(data) { console.log("log: " + data); }); </script> Obviously, {{ user.username }} will be replaced by the username of the currently logged in user, in this example the username is "alp". Now, every time the page gets refreshed, the console output is: connected log: hello alp Therefore, invoking messages and sending responses works. But now comes the tricky part. Problems The response "hello alp" is sent only to the invoker of the socket.io message. I want to broadcast a message to all connected clients, so that they can be informed in realtime if a new user joins the party (for example in a chat application). So, here are my questions: How can i send a broadcast message to all connected clients? How can i send a broadcast message to multiple connected clients that are subscribed on a specific channel? How can i send a broadcast message anywhere in my python code (outside of the BaseConnection class)? Would this require some sort of Socket.IO client for python or is this builtin with TornadIO2? All these broadcasts should be done in a reliable way, so i guess websockets are the best choice. But i am open to all good solutions.

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• Fixed point math in c#?

  - by x4000

  Hi there, I was wondering if anyone here knows of any good resources for fixed point math in c#? I've seen things like this (http://2ddev.72dpiarmy.com/viewtopic.php?id=156) and this (http://stackoverflow.com/questions/79677/whats-the-best-way-to-do-fixed-point-math), and a number of discussions about whether decimal is really fixed point or actually floating point (update: responders have confirmed that it's definitely floating point), but I haven't seen a solid C# library for things like calculating cosine and sine. My needs are simple -- I need the basic operators, plus cosine, sine, arctan2, PI... I think that's about it. Maybe sqrt. I'm programming a 2D RTS game, which I have largely working, but the unit movement when using floating-point math (doubles) has very small inaccuracies over time (10-30 minutes) across multiple machines, leading to desyncs. This is presently only between a 32 bit OS and a 64 bit OS, all the 32 bit machines seem to stay in sync without issue, which is what makes me think this is a floating point issue. I was aware from this as a possible issue from the outset, and so have limited my use of non-integer position math as much as possible, but for smooth diagonal movement at varying speeds I'm calculating the angle between points in radians, then getting the x and y components of movement with sin and cos. That's the main issue. I'm also doing some calculations for line segment intersections, line-circle intersections, circle-rect intersections, etc, that also probably need to move from floating-point to fixed-point to avoid cross-machine issues. If there's something open source in Java or VB or another comparable language, I could probably convert the code for my uses. The main priority for me is accuracy, although I'd like as little speed loss over present performance as possible. This whole fixed point math thing is very new to me, and I'm surprised by how little practical information on it there is on google -- most stuff seems to be either theory or dense C++ header files. Anything you could do to point me in the right direction is much appreciated; if I can get this working, I plan to open-source the math functions I put together so that there will be a resource for other C# programmers out there. UPDATE: I could definitely make a cosine/sine lookup table work for my purposes, but I don't think that would work for arctan2, since I'd need to generate a table with about 64,000x64,000 entries (yikes). If you know any programmatic explanations of efficient ways to calculate things like arctan2, that would be awesome. My math background is all right, but the advanced formulas and traditional math notation are very difficult for me to translate into code.

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• GCD and AppleEvents / NSOperationQueue and AppleScript

  - by mahal tertin

  As i understood, the threads provided by GCD do have a runloop but no source/port. Now i use some of methods that call AppleScripts thru AppleEvents inside an NSOperationQueue. And sometimes my app crashes with following stacktrace. my questions: Usage of AppleScript inside a NSInvocationOperation or NSBlockOperation Usage of AppleEvents inside GCD-Threads do i have to add a source / port to a runloop of a gcd-thread before using AppleEvents? do i have to add a source / port to a runloop of a gcd-thread before using [CATransaction commit]? do i have to add a source / port to a runloop of a gcd-thread before using [NSObject performSelectorAfterDelay...] ? if yes, how? can i simply call CFRunLoopRunInMode(kCFRunLoopDefaultMode, 5.0, false); /// or 30 or the defined timeout of appleevent? .. Thread 9: Dispatch queue: com.apple.root.default-priority 0 libSystem.B.dylib 0x00007fff88276e82 semaphore_wait_signal_trap 10 1 libSystem.B.dylib 0x00007fff8827c3cd pthread_mutex_lock 469 2 com.apple.applescript 0x000000011d3d461f AppleScriptComponent 50 3 com.apple.applescript 0x000000011d3edbcc AGenericCall::Delegate(ComponentInstanceRecord*) 46 4 com.apple.applescript 0x000000011d3ed520 AGenericManager::HandleOSACall(ComponentParameters*) 54 5 com.apple.applescript 0x000000011d3ed4b0 GenericComponent 219 6 com.apple.openscripting 0x00007fff8381c6da OSAExecuteEvent 63 7 com.apple.Foundation 0x00007fff86f320d8 -[NSAppleScript(NSPrivate) _executeAppleEvent:withMode:error:] 161 8 xxx 0x0000000100048af0 -[TCallScript callScript:withArrayOfParameters:] 480 9 xxx 0x0000000100048ffd -[TCallScript callHandler:withParameters:] 477 10 xxx 0x0000000100036032 -[ZFOpenWindowController getSafariItemForCurrentTabForWindow:] 66 11 xxx 0x00000001000346af -[ZFOpenWindowController refreshWindowList:] 1679 12 xxx 0x000000010003541c -[ZFOpenWindowController bringZFToForegroundZoomOut:orJustLinkFrontMost:toItem:] 2988 13 xxx 0x0000000100053556 __-[ZFSelectionTool openWithPreferredApplication:]_block_invoke_516 54 14 com.apple.Foundation 0x00007fff86ed87d9 -[NSBlockOperation main] 140 15 com.apple.Foundation 0x00007fff86ec906d -[__NSOperationInternal start] 681 16 com.apple.Foundation 0x00007fff86ec8d23 ____startOperations_block_invoke_2 99 17 libSystem.B.dylib 0x00007fff882b2ce8 _dispatch_call_block_and_release 15 18 libSystem.B.dylib 0x00007fff88291279 _dispatch_worker_thread2 231 19 libSystem.B.dylib 0x00007fff88290bb8 _pthread_wqthread 353 20 libSystem.B.dylib 0x00007fff88290a55 start_wqthread 13 ... Thread 11 Crashed: Dispatch queue: com.apple.root.default-priority 0 com.apple.applescript 0x000000011d40f658 BCHandleError() 182 1 com.apple.applescript 0x000000011d4059ca UASExecute1() 2546 2 com.apple.applescript 0x000000011d3dd1d5 ASExecuteEvent(AEDesc const*, unsigned int, int, unsigned int*) 695 3 ...ple.CoreServices.CarbonCore 0x00007fff85388e04 CallComponentFunction 28 4 com.apple.applescript 0x000000011d3d4cad AppleScriptComponent 1728 5 com.apple.applescript 0x000000011d3edbcc AGenericCall::Delegate(ComponentInstanceRecord*) 46 6 com.apple.applescript 0x000000011d3ed520 AGenericManager::HandleOSACall(ComponentParameters*) 54 7 com.apple.applescript 0x000000011d3ed4b0 GenericComponent 219 8 com.apple.openscripting 0x00007fff8381c6da OSAExecuteEvent 63 9 com.apple.Foundation 0x00007fff86f320d8 -[NSAppleScript(NSPrivate) _executeAppleEvent:withMode:error:] 161 10 xxx 0x0000000100048af0 -[TCallScript callScript:withArrayOfParameters:] 480 11 xxx 0x0000000100048ffd -[TCallScript callHandler:withParameters:] 477 12 xxx 0x0000000100035c67 -[ZFOpenWindowController getItemForAXDocumentOfFrontMostWindow] 119 13 xxx 0x00000001000359f1 -[ZFOpenWindowController getItemForFrontMostWindow:] 721 14 xxx 0x00000001000348ac -[ZFOpenWindowController bringZFToForegroundZoomOut:orJustLinkFrontMost:toItem:] 60 15 xxx 0x0000000100053556 __-[ZFSelectionTool openWithPreferredApplication:]_block_invoke_516 54 16 com.apple.Foundation 0x00007fff86ed87d9 -[NSBlockOperation main] 140 17 com.apple.Foundation 0x00007fff86ec906d -[__NSOperationInternal start] 681 18 com.apple.Foundation 0x00007fff86ec8d23 ____startOperations_block_invoke_2 99 19 libSystem.B.dylib 0x00007fff882b2ce8 _dispatch_call_block_and_release 15 20 libSystem.B.dylib 0x00007fff88291279 _dispatch_worker_thread2 231 21 libSystem.B.dylib 0x00007fff88290bb8 _pthread_wqthread 353 22 libSystem.B.dylib 0x00007fff88290a55 start_wqthread 13

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• trouble with utf-8 chars & apache2 rewrite rules

  - by tixrus

  I see the post http://stackoverflow.com/questions/2565864/validating-utf-8-in-htaccess-rewrite-rule and I think that is great, but a more fundamental problem I am having first: I needed to expand to handle utf-8 chars for query string parameters, names of directories, files, and used in displays to users etc. I configured my Apache with DefaultCharset utf-8 and also my php if that matters. My original rewrite rule filtered everything except regular A-Za-z and underscore and hyphen. and it worked. Anything else would give you a 404 (which is what I want!) Now, however it seems that everything matches, including stuff I don't want, however, although it seems to match it doesn't go in the query string unless it is a regular A-Za-z_- character string. I find this confusing, because the rule says put whatever you matched into the query string: Here is the original rule: RewriteRule ^/puzzle/([A-Za-z_-]+)$ /puzzle.php?g=$1 [NC] and here is the revised rule: RewriteRule ^/puzzle/(\w+)$ /puzzle.php?g=$1 [NC] I made the change because somewhere I read that \w matches ALL the alpha chars where as A-Zetc. only matches the ones without accents and stuff. It doesn't seem to matter which of those rules I use: Here is what happens: In the application I have this: echo $_GET['g']; If I feed it a url like http://mydomain.com/puzzle/USA it echoes out "USA" and works fine. If I feed it a url like http://mydomain.com/puzzle/México it echoes nothing for that and warns me that index g is not defined and of course doesn't get resources for Mexico. if I feed it a url like http://mydomain.com/puzzle/fuzzle/buzzle/j.qle it does the same thing. This last case should be a 404! And it does this no matter which of the above rules I use. I configured a rewrite log RewriteLogLevel 5 RewriteLog /opt/local/apache2/logs/puzzles.httpd.rewrite but it is empty. Here is from the regular access log (it gives a status of 200) [26/May/2010:11:21:42 -0700] "GET /puzzle/M%C3%A9xico HTTP/1.1" 200 342 [26/May/2010:11:21:54 -0700] "GET /puzzle/M/l.foo HTTP/1.1" 200 342 What can I do to get these $%#$@(*#@!!! characters but not slash, dot or other non-alpha into my program, and once there, will it decode them correctly??? Would posix char classes work any better? Is there anything else I need to configure?

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• Use native HBitmap in C# while preserving alpha channel/transparency. Please check this code, it works on my computer...

  - by David

  Let's say I get a HBITMAP object/handle from a native Windows function. I can convert it to a managed bitmap using Bitmap.FromHbitmap(nativeHBitmap), but if the native image has transparency information (alpha channel), it is lost by this conversion. There are a few questions on Stack Overflow regarding this issue. Using information from the first answer of this question (How to draw ARGB bitmap using GDI+?), I wrote a piece of code that I've tried and it works. It basically gets the native HBitmap width, height and the pointer to the location of the pixel data using GetObject and the BITMAP structure, and then calls the managed Bitmap constructor: Bitmap managedBitmap = new Bitmap(bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); As I understand (please correct me if I'm wrong), this does not copy the actual pixel data from the native HBitmap to the managed bitmap, it simply points the managed bitmap to the pixel data from the native HBitmap. And I don't draw the bitmap here on another Graphics (DC) or on another bitmap, to avoid unnecessary memory copying, especially for large bitmaps. I can simply assign this bitmap to a PictureBox control or the the Form BackgroundImage property. And it works, the bitmap is displayed correctly, using transparency. When I no longer use the bitmap, I make sure the BackgroundImage property is no longer pointing to the bitmap, and I dispose both the managed bitmap and the native HBitmap. The Question: Can you tell me if this reasoning and code seems correct. I hope I will not get some unexpected behaviors or errors. And I hope I'm freeing all the memory and objects correctly. private void Example() { IntPtr nativeHBitmap = IntPtr.Zero; /* Get the native HBitmap object from a Windows function here */ // Create the BITMAP structure and get info from our nativeHBitmap NativeMethods.BITMAP bitmapStruct = new NativeMethods.BITMAP(); NativeMethods.GetObjectBitmap(nativeHBitmap, Marshal.SizeOf(bitmapStruct), ref bitmapStruct); // Create the managed bitmap using the pointer to the pixel data of the native HBitmap Bitmap managedBitmap = new Bitmap( bitmapStruct.bmWidth, bitmapStruct.bmHeight, bitmapStruct.bmWidth * 4, PixelFormat.Format32bppArgb, bitmapStruct.bmBits); // Show the bitmap this.BackgroundImage = managedBitmap; /* Run the program, use the image */ MessageBox.Show("running..."); // When the image is no longer needed, dispose both the managed Bitmap object and the native HBitmap this.BackgroundImage = null; managedBitmap.Dispose(); NativeMethods.DeleteObject(nativeHBitmap); } internal static class NativeMethods { [StructLayout(LayoutKind.Sequential)] public struct BITMAP { public int bmType; public int bmWidth; public int bmHeight; public int bmWidthBytes; public ushort bmPlanes; public ushort bmBitsPixel; public IntPtr bmBits; } [DllImport("gdi32", CharSet = CharSet.Auto, EntryPoint = "GetObject")] public static extern int GetObjectBitmap(IntPtr hObject, int nCount, ref BITMAP lpObject); [DllImport("gdi32.dll")] internal static extern bool DeleteObject(IntPtr hObject); }

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• iGoogle Stack Overflow Gadget [closed]

  - by Charango

  Since SO's question database is becoming an excellent first point of call for finding answers to coding problems, some people (like me) might like to be able to fire up searches from their iGoogle home page, among the other searches you might launch from there. I've created a very simple gadget to do this, and put the source below. My hope is that this might provide a foundation on which community members with better ideas for performing this function, or ideas for enhancing it, can update it. Perhaps we could make it configurable to search via a site scope search from Google and / or a question search, for instance. I've hosted and registered this first version but if anyone makes changes and can host a new version / new pics elsewhere, please feel free. <?xml version="1.0" encoding="UTF-8"?> <Module> <ModulePrefs title="Stack Overflow Search" author="Community Wiki" author_email="[email protected]" author_affiliation="Stack Overflow" author_location="The Internet" author_aboutme="All sorts" author_link="http://stackoverflow.com" author_quote="Hofstadter's Law: It always takes longer than you expect, even when you take into account Hofstadter's Law." description="Stack Overflow is rapidly becoming one of the best resources for finding answers to your programming questions. This gadget adds a question search box to your iGoogle homepage" screenshot="http://arkios-solutions.com/misc/sogadget/SOGadget.png" thumbnail="http://arkios-solutions.com/misc/sogadget/SOGadget_Thumbnail.png" singleton="true" title_url="http://stackoverflow.com" /> <Content type="html"><![CDATA[ <img src="http://i.stackoverflow.com/Content/Img/stackoverflow-logo-250.png" alt="Stackoverflow Logo"/> <div style="font-family:arial;font-size:0.8em;"> This gadget allows you to search the Stack Overflow question database. </div> <form name='SOQueryForm' action="http://stackoverflow.com/search" method="get" target="new"> <p>Your question: <input type='text' size='34' name='q' /></p> <p><input type='submit' value='Go' /></p> </form> ]]> </Content> </Module> The source / installable gadget xml are also hosted here.

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• CGContextFillEllipseInRect: invalid context

  - by hakewake

  Hi all, when I launch my app, I keep getting this CGContextFillEllipseInRect: invalid context error. My app is simply to make the circle 'pinchable'. The debugger shows me this: [Session started at 2010-05-23 18:21:25 +0800.] 2010-05-23 18:21:27.140 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.144 Erase[8045:207] New value of counter is 1 2010-05-23 18:21:27.144 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.144 Erase[8045:207] New value of counter is 2 2010-05-23 18:21:27.144 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.144 Erase[8045:207] New value of counter is 3 2010-05-23 18:21:27.145 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.145 Erase[8045:207] New value of counter is 4 2010-05-23 18:21:27.148 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.149 Erase[8045:207] New value of counter is 5 2010-05-23 18:21:27.150 Erase[8045:207] I'm being redrawn. Sun May 23 18:21:27 Sidwyn-Kohs-MacBook-Pro.local Erase[8045] <Error>: CGContextFillEllipseInRect: invalid context 2010-05-23 18:21:27.150 Erase[8045:207] New value of counter is 6 My implementation file is: // // ImageView.m // Erase // #import "ImageView.h" #import "EraseViewController.h" @implementation ImageView -(void)setNewRect:(CGRect)anotherRect{ newRect = anotherRect; } - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { newRect = CGRectMake(0,0,0,0); ref = UIGraphicsGetCurrentContext(); } return self; } - (void)drawRect:(CGRect)rect { static int counter = 0; CGRect veryNewRect = CGRectMake(30.0, 210.0, 60.0, 60.0); NSLog(@"I'm being redrawn."); if (counter == 0){ CGContextFillEllipseInRect(ref, veryNewRect); } else{ CGContextFillEllipseInRect(ref, rect); } counter++; NSLog(@"New value of counter is %d", counter); } - (void)setNeedsDisplay{ [super setNeedsDisplay]; [self drawRect:newRect]; } - (void)dealloc { [super dealloc]; } @end I've got two questions: 1) Why is it updating counter 6 times? I removed the line [super setNeedsDisplay]; but it becomes 4 times. 2) What is that invalid context error? Thanks guys.

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• Non-linear regression models in PostgreSQL using R

  - by Dave Jarvis

  Background I have climate data (temperature, precipitation, snow depth) for all of Canada between 1900 and 2009. I have written a basic website and the simplest page allows users to choose category and city. They then get back a very simple report (without the parameters and calculations section): The primary purpose of the web application is to provide a simple user interface so that the general public can explore the data in meaningful ways. (A list of numbers is not meaningful to the general public, nor is a website that provides too many inputs.) The secondary purpose of the application is to provide climatologists and other scientists with deeper ways to view the data. (Using too many inputs, of course.) Tool Set The database is PostgreSQL with R (mostly) installed. The reports are written using iReport and generated using JasperReports. Poor Model Choice Currently, a linear regression model is applied against annual averages of daily data. The linear regression model is calculated within a PostgreSQL function as follows: SELECT regr_slope( amount, year_taken ), regr_intercept( amount, year_taken ), corr( amount, year_taken ) FROM temp_regression INTO STRICT slope, intercept, correlation; The results are returned to JasperReports using: SELECT year_taken, amount, year_taken * slope + intercept, slope, intercept, correlation, total_measurements INTO result; JasperReports calls into PostgreSQL using the following parameterized analysis function: SELECT year_taken, amount, measurements, regression_line, slope, intercept, correlation, total_measurements, execute_time FROM climate.analysis( $P{CityId}, $P{Elevation1}, $P{Elevation2}, $P{Radius}, $P{CategoryId}, $P{Year1}, $P{Year2} ) ORDER BY year_taken This is not an optimal solution because it gives the false impression that the climate is changing at a slow, but steady rate. Questions Using functions that take two parameters (e.g., year [X] and amount [Y]), such as PostgreSQL's regr_slope: What is a better regression model to apply? What CPAN-R packages provide such models? (Installable, ideally, using apt-get.) How can the R functions be called within a PostgreSQL function? If no such functions exist: What parameters should I try to obtain for functions that will produce the desired fit? How would you recommend showing the best fit curve? Keep in mind that this is a web app for use by the general public. If the only way to analyse the data is from an R shell, then the purpose has been defeated. (I know this is not the case for most R functions I have looked at so far.) Thank you!

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• Looking for efficient scaling patterns for Silverlight application with distributed text-file data s

  - by Edward Tanguay

  I'm designing a Silverlight software solution for students and teachers to record flashcards, e.g. words and phrases that students find while reading and errors that teachers notice while teaching. Requirements are: each person publishes his own flashcards in a file on a web server, e.g. http://:www.mywebserver.com/flashcards.txt other people subscribe to that person's flashcards by using a Silverlight flashcard reader that I have developed and entering the URLs of flashcard files they want to subscribe to, URLs and imported flashcards being saved in IsolatedStorage the flashcards.txt file has the following simple format: title, then blocks of question/answers: Jim Smith's flashcards from English class 53-222, winter semester 2009 ==fla Das kann nicht sein. That can't be. ==fla Es sei denn, er kommt nicht. Unless he doesn't come. The user then makes public the URL to his flashcard file and other readers begin reading in his flashcards. In order to lower the bar for non-technical users to contribute, it will even be possible for them to save this text in a Google Document, which they publish and distribute the URL. The flashcard readers will then recognize it is a google document and perform the necessary screen scraping to get at the raw text. I have two technical questions about this approach: What is a best way to plan now for scalability issues: e.g. if your reader is subscribed to 10 flashcard files that are each 200K, it will have to download 2MB of text just to find out if any new flashcards are available. Or can I somehow accurately and consistently get at the last update date/time of text files on servers and published google docs? Each reader will have the ability to allow the person to test himself on imported flashcards and add meta information to them, e.g. categorize them, edit them, etc. This information will be stored in IsolatedStorage along with the important flashcards themselves. What is a good pattern to allow these readers to share and synchronize this meta data, e.g. so when you are looking at a flashcard you can see that 5 other people have made corrections to it. The best solution I can think of now is that the Silverlight readers will have to republish their data to a central database, but then there is the problem of uniquely identifying each flashcard, the best approach seems to be URL + position-in-file, or even better URL + original text of both question and answer fields, but both of these have their obvious drawbacks. The main requirement is that the bar for participation is kept as low as possible, i.e. type text in a google document, publish it, distribute the URL, and you're publishing within the flashcard community. So I want to come up with the most efficient technical solutions in order to compensate for the lack of database, lack of unique ids, etc. For those who have designed or developed similar non-traditional, distributed database projects like this, what advice, experience or best-practice tips you can share on the above two points?

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• Winform radiobutton data binding

  - by Rajarshi

  I am following the "Presentation Model" design pattern suggested by Martin Fowler for my GUI architecture in a Windows Forms project. "The essence of a Presentation Model is of a fully self-contained class that represents all the data and behavior of the UI window, but without any of the controls used to render that UI on the screen. A view then simply projects the state of the presentation model onto the glass...." - Martin Fowler Read more about this pattern at www.martinfowler.com/eaaDev/PresentationModel.html I am finding the concept very fluid and easy to understand except this one issue of data binding RadioButtons to properties on the Data/Domain object. Suposing I have a Windows Form with 3 radio buttons to depict some "Mode" options as - Auto Manual Import How can I use boolean properties on Data/Domain Objects to DataBind to these buttons? I have tried many ways but to no avail. For example I would like to code like - rbtnAutoMode.DataBindings.Add("Text", myBusinessObject, "IsAutoMode"); rbtnManualMode.DataBindings.Add("Text", myBusinessObject, "IsManualMode"); rbtnImportMode.DataBindings.Add("Text", myBusinessObject, "IsImportMode"); There should be a fourth property like "SelectedMode" on the data/domain object which at the end should depict a single value like "SelectedMode = Auto". I am trying to update this property when any of the "IsAutoMode", "IsManualMode" or "IsImportMode" is changed, e.g. through the property setters. I have INotifyPropertyChanged implemented on my data/domain object so, updating any data/domain object property automatically updates my UI controls, that's not an issue. There is a good example of binding 2 radio buttons here - http://stackoverflow.com/questions/344964/how-do-i-use-databinding-with-windows-forms-radio-buttons but I am missing the link while implementing the same with 3 buttons. I am having very erratic behaviors for the Radio Buttons. I hope I was able to explain reasonably. I am actually in a hurry and could not put a detailed code on post, but any help in this regard is appreciated. There is a simple solution to this issue by exposing a method like - public void SetMode(Modes mode) { this._selectedMode = mode; } which could be called from the "CheckedChanged" event of the Radio Buttons from the UI and would perfectly set the "SelectedMode" on the business object, but I need to stretch the limits to verify whether this can be done by DataBinding.

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• H.264 over RTP - Identify SPS and PPS Frames

  - by Toby

  I have a raw H.264 Stream from an IP Camera packed in RTP frames. I want to get raw H.264 data into a file so I can convert it with ffmpeg. So when I want to write the data into my raw H.264 file I found out it has to look like this: 00 00 01 [SPS] 00 00 01 [PPS] 00 00 01 [NALByte] [PAYLOAD RTP Frame 1] // Payload always without the first 2 Bytes -> NAL [PAYLOAD RTP Frame 2] [... until PAYLOAD Frame with Mark Bit received] // From here its a new Video Frame 00 00 01 [NAL BYTE] [PAYLOAD RTP Frame 1] .... So I get the SPS and the PPS from the Session Description Protocol out of my preceding RTSP communication. Additionally the camera sends the SPS and the PPSin two single messages before starting with the video stream itself. So I capture the messages in this order: 1. Preceding RTSP Communication here ( including SDP with SPS and PPS ) 2. RTP Frame with Payload: 67 42 80 28 DA 01 40 16 C4 // This is the SPS 3. RTP Frame with Payload: 68 CE 3C 80 // This is the PPS 4. RTP Frame with Payload: ... // Video Data Then there come some Frames with Payload and at some point a RTP Frame with the Marker Bit = 1. This means ( if I got it right) that I have a complete video frame. Afer this I write the Prefix Sequence ( 00 00 01 ) and the NALfrom the payload again and go on with the same procedure. Now my camera sends me after every 8 complete Video Frames the SPS and the PPS again. ( Again in two RTP Frames, as seen in the example above ). I know that especially the PPS can change in between streaming but that's not the problem. My questions are now: 1. Do I need to write the SPS/PPS every 8th Video Frame? If my SPS and my PPS don't change it should be enough to have them written at the very beginning of my file and nothing more? 2. How to distinguish between SPS/PPS and normal RTP Frames? In my C++ Code which parses the transmitted data I need make a difference between the RTP Frames with normal Payload an the ones carrying the SPS/PPS. How can I distinguish them? Okay the SPS/PPS frames are usually way smaller, but that's not a save call to rely on. Because if I ignore them I need to know which data I can throw away, or if I need to write them I need to put the 00 00 01 Prefix in front of them. ? Or is it a fixed rule that they occur every 8th Video Frame?

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• EventDispatcher between an as and an fla?

  - by Christopher Richa

  Hi everyone. I am making a fighting game in Flash and while I have everything running, I am missing something: a victory/loss screen. Logically, I know how to do it: if character.hp < 0 { character.dead = true; dispatchevent("death", event) } My problem is that I have no idea as to how to code it. I know I will use two classes and my two .fla files (unless I am wrong). I have two .fla files that are in play here: the Menu.fla file and the Arena.fla file. Menu.fla contains the entire navigation of the game, options, character selection screens, etc. and when it is time for the player to engage in battle, it loads the Arena.fla file, which contains only the backgrounds (depending on the selected stage) and for now is set to a length of one frame only. For Arena.fla, the real action happens in my classes, but logically, I would only need HP.as and Character.as. In Character.as, I have declared the following variable: var isDead:Boolean = false; //is character dead? In HP.as, believe I should have the following: if(currentHp<0) { currentHp = 0; character.isDead = true; //declared as var `character:Object;` EventDispatcher.dispatchEventListener("playerDead", playerDead); } And finally, in Arena.fla, I want to be able to detect the above-mentioned eventlistener and simply move on to a second frame which will display a message in the style of "PLAYER ONE HAS WON" or "PLAYER ONE HAS LOST" with a button that will allow me to go back to the character selection screen. This is the first part in which I am stuck: how do I detect the dispatched event listener in my main .fla file? Secondly, if the player clicks on the "CONTINUE" button, which displays regardless if the player has won or lost, how can my Menu.fla (which loads the Arena.swf) detect this click event, unload the game, and go back to the character selection screen? Thank you in advance for helping me out. I realize this is a lot of text but it's the most descriptive I can be. If you have any questions or need any clarification concerning my question, feel free to speak up. -Christopher

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• Convert a PDF to a Transparent PNG with GhostScript

  - by Jonathon Wolfe

  Hi all. I am attempting, unsuccessfully, to use Ghostscript to rasterize PDF files with a transparent background to PNG files with a transparent background. I've searched high and low for questions from others attempting the same thing and none of the posted solutions, which as far as I can tell come down to specifying -sDEVICE=pngalpha, have worked with my test files. At this point I would really appreciate any advice or tips a more experienced hand could provide. My test PDF is located here: http://www.kolossus.com/files/test.pdf It could be that the issue is with this file, but I doubt it. As far as I can tell, it has no specified background, and when I open the file with a transparency-aware app like Photoshop or Illustrator, sure enough it displays with a transparent background. However, when opened with an application like Adobe Reader the file is rendered with a white background. I believe that this has more to do with the application rendering the PDF than with the PDF itself -- apps like Adobe Reader assume you want to see what a printed document will look like and therefore always show a white canvas behind the artwork -- but I can't be sure. The gs command I'm using is: gs -dNOPAUSE -dBATCH -sDEVICE=pngalpha -r72 -sOutputFile=test.png test.pdf This produces a PNG that has transparent pixels outside of the bounding box of the artwork in the file, but all pixels that are inside the artwork's bounding box are rasterized against a white background. This is a problem for me, as my artwork has drop shadows and antialiased edges that need to be preserved in the final output, and can't just be postprocessed out with ImageMagick. A sample of my PNG output is at the same location as the pdf above, with .png at the end (stackoverflow won't let me include more than one url in my post). Interestingly, I see no effects from using the -dBackgroundColor flag, even if I set it to something non-white like -dBackgroundColor=16#ff0000. Perhaps my understanding of the syntax of this flag is wrong. Also interestingly, I see no effects from using the -dTextAlphaBits=4 -dGraphicsAlphaBits=4 flags to try to enable subpixel antialiasing. I would also appreciate any advice on how to enable subpixel antialiasing, especially on text. Finally, I'm using GPL Ghostscript 8.64 on Mac OS 10.5.7, and the rendering workflow I'm trying to get set up is to generate transparent PNG images from PDFs output by PrinceXML. I'm calling Ghostscript directly for the rasterization instead of using ImageMagick because ImageMagick delegates to Ghostscript for PDF rasterization and I should be able to control the rasterization better by calling GS directly. Thanks for your help. -Jon Wolfe

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• do you want try ? [closed]

  - by gemxia

  Only with time and hard work, that can you get an IT certification. Although there are hundreds of certifications for you to pick from, the basic steps to get certified are the same. The following steps are certain to clear your puzzles about the preparation process of your <. The first step to take is choosing a certification. It is simple but at the same time very important. Make sure to choose the certifications that are respected in your industries. The second step you should take is to evaluate your experience. Find out what skills and experience the IBM certification is expecting. Then, decide what type of training is suitable for you. Preparation books will certainly not make you an expert in subjects you’re not already an expert in. But, for the subject areas you know little or nothing about, a study guide provides you clues and guidance about what the important information from those subjects is when it comes to passing the Examkiller IBM examination exam. Visit certification forums during your 000-M62 certification exam preparation. In this way, you can learn from others’ mistakes and example, meanwhile help your own studies. Achieving your goals without proper training is a sure road to failure. Knowing about a topic and having special expertise in it are completely different. One cannot be an expert in the IT industry without the proper foundation. Taking a training class for Examkiller IBM exam might be a guaranteed way. When the economy dips and budgets get tightened, one of the first things to go from corporate spending is training. There are plenty of courses, boot camps and cram sessions that promise to prepare you for the IBM exam, but they are exceptionally expensive. As much as possible, for your own benefit, you should look for resources that are free. Vendor of IBM offers free resource in their sites. These practice exams are the closest to the real exams. If you think that you have got ready for the exam, you can take the fourth now, which is registering your exam. Even if you have passed your <, yet you can’t relax, since there are still so many certifications ahead. If you have just memorized some questions and answers, excepting a fluke, then, don’t take the IBM test exam, until you really have the experience and skills the certification requires.

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